Electrodeposition of metals



Patented Jan. 31, 1933 UNITED STATES PATENT OFFICE FRANK O. MATEEBS, OF BLOOMINGTON, INDIANA, AND LOUIS BATEMAN, OF EAST LA'NSDTG, MICHIGAN, ASSIGNORS TO UNITED STATES SMELTING, REFINING & MIN- ING- COMIPANY, OF PORTLAND, MAINE, ,A CORPORATION OF MAINE ELECTRODEPOSITION OF METALS No Drawing.

The invention relates to electrodeposition of metals and more particularly to electrolytic refining of lead by electrodeposition of the metal from aqueous solutions of its salts.

It is the practlce in the electrolytic refining of metals to employ so-called addition reagents in aqueous solutions of the compounds of the metals from which the metals are deposited. The role which such addition reagents plays in the actual electrodeposition of metals is not understood, but their use results in the production of smooth deposits which are so finely crystalline that they may be considered as being substantially non-crystalline. The present'invention is based on the discovery of new reagents of this character for use with an electrolyte containing dithionic acid in the electrodeposition of lead, which process has marked advantages over prior reagents employed. The proper amount of reagent to be used depends upon the chemical composition, the temperature, and the rate of circulation of the electrolyte, the amount and character of the impurities in the electrolyte, and the current density employed.

The new reagents are classified as hydroxy compounds of coal tar which include phenol, resorcinol, cresol, and beta-na hthol. Cresol is an example of this class 0 hydroxy compounds of coal tar which may be used as addition reagents with especially good results, but it will be understood that, except as limited by the terms of the claims, the invention also includes the use of the others in the above category.

We have discovered in the electrolytic refining of lead that hydroxy compounds of coal tar, such, for instance, as cresol, may be used as an addition reagent in dithionic acid electrolytes with remarkable advantageous results. It may be used to replace many of the addition reagents now commonly used and because of its comparatively low cost, substantial economy may be thereby effected. It may be used alone or in partial replacement of some of the commonly used addition reagents, effecting not only an economy thereby, but permitting a substitution to take place in old electrolyte, thus avoiding the cost of 0 new electrolyte when changing over to this Application filed January 9, 1981. Serial No. 507,754.

new addition reagent. In many cases, it produces a deposit of the lead upon the cathode superior to deposits obtained by other addition reagents, increasing thereby the efliciency of the operation, and resulting in important economy in the power consumption. No accumulation in the electrolyte of substances which might finally cause the formation of non-adherent and coarsely crystalline deposits has been noticed when this addition reagent is used, as has been noticed when certain addition reagents heretofore known have been used;

While cresol alone or in combination with other addition reagents gives satisfactory repyrogallol and glue give satisfactory results in the dithionic acid electrolyte.

The composition of the electrolyte may vary and likewise the amounts of reagents may vary without materially aifecting the character of the deposit. An electrolyte containing 5% lead dithionate and 2% free dithionic acid to which has been added .8% cresol and 15% glue has given a satisfactory cathode deposit and a high current efliciency. With the same electrolyte good deposits have been obtained with .04% betanaphthol and 02% glue and likewise with 1% phenol and 25% glue. I

Having thus described the invention, what is claimed is: a 1

1. That improvement in the electrodeposition of lead from electrolytescontaining dithionic acid which consists of the use of a tar as an addition reagent in the acid electrolyte.

3. That improvement in the electrodeposition of lead from electrolytes contaimng dithionic acid which consists of the use of a compound of a class consisting of phenol, cresol, resorcinol and beta-naphthol as an addition reagent in conjunction with glue in the acid electrolyte.

4. That im rovement in the electrodeposition of lea from electrolytes containing dithionic acid which consists of the use of a hydroxy compound occurring in coal tar in conjunction with glue as an addition reagent in the acid electrolyte. v i

5. That improvement in the electrodeposition of lead from electrolytes containing dithionic acid which consists of the use of a cychc hydroxy compound occurring in coal tar in conjunction with glue as an addition reagent in the acid electrolyte.

6. That improvement in the electrodeposition of lead from electrolytes containing dithionic acid which consists of the use of a compound of aclass consisting of phenol, cresol,resorcino1, and beta-napht 01 as an addition reagent in conjunction with other addition reagents in the acid electrolyte.

7. That improvement in the electrodeposition of lead from electrolytes containing dithionic acid which consists in the use ofa .compound of the class consistin of phenol,

' cresol, resorcinol, and beta-napht 01 as an addition reagent. v

In testimony whereof we have signed our names to this s gcification.

RANK 0. MATHERS. LOUIS BATEMAN. 

